This invention relates to novel benzoquinone compounds and their use. The new compounds of the present invention are inhibitors of both the cyclooxygenase (CO) and lipoxygenase (LO) enzymes, and are of use in the treatment or alleviation of allergic or inflammatory conditions in mammals including human.
Arachidonic acid is known to be the biological precursor of several groups of endogenous metabolites, prostaglandins including prostacyclins, thromboxanes and leukotrienes. The first step of the arachidonic acid metabolism is the release of esterified arachidonic acid and related unsaturated fatty acids from membrane phospholipids, via the action of phospholipase. Free fatty acids are then metabolized either by cyclooxygenase to produce the prostaglandins and thromboxanes or by lipoxygenase to generate hydroperoxy fatty acids which may be further converted to the leukotrienes. The prostaglandins exhibit diverse physiological effects depending upon their structure. For example, PGE and PGA inhibit gastric secretion as well as lower arterial blood pressure. The thromboxane, especially, thromboxane A.sub.2 is a potent vasoconstrictor and platelet aggregatory substance. The leukotrienes are the biological source of the slow reacting substance of anaphylaxis (SRS-A), a chemical mediator in allergic bronchial asthma.
Aspirin and most other non-steroidal antiinflammatory drugs inhibit the cyclooxygenase enzyme. Both antiinflammatory activity and analgesic activity associated with these drugs are rationalized in terms of their inhibition of the action of cyclooxygenase. The lipoxygenase inhibiting activity of one agent, AA861 [2,3,5-trimethyl-6-(12-hydroxy-5,10-cyclodecadiynyl)-1,4-benzoquinone], has been reported [see, Yoshimoto et al., Biochem, et Biophys. 713, 470-473 (1982)]. CGS-5391B [(C. E. Hock et al., Prostaglandins, 28, 557-571 (1984)]has recently become known as a combination cycloxygenase and lipoxygenase inhibitor.
Besides, PCT Patent Application PCT/JP84/00452 (WO 85/01289) and Japanese patent publication No. 107958/1988 describe and claim a number of benzoxazolone and benzothiazolone derivatives useful for the treatment of inflammatory conditions and thrombosis.